Where is Restlet's OAuth extension in Maven?

I wanted to try out Restlet's OAuth extension in a Java EE project. When going to the download page and selecting maven, a number of available extensions are listed, but the OAuth extension isn't.

According to the Javadocs, there is an org.restlet.ext.oauth package, but I don't know where I can find it in the Maven repository. It isn't in the main maven artifact, and there isn't any artifact whose description mentions "OAuth". Following the naming convention, I tried to add the artifact org.restlet.ext.oauth, but it doesn't exist (which is not surprising, as it isn't mentioned on the above-liked download page).

Where can I find the org.restlet.ext.oauth package the restlet Maven repository?